말그대로 외국인 투자가 되는데 만약 제 명의로 구입을 하고 차후 미국내에서 증여를 할경우 증여세가 얼마나 되는지 궁금합니다..”--->However, in US, the donor,you, is generally responsible for paying the gift tax. Under special arrangements the donee, your son, may agree to pay the tax instead. However, you, as a non_US person( I assume that you are not a US national, citizen or a green card holder), are NOT liable for the gift tax in the US. So, you do not need to pay any gift tax in the US, neither does your son. Even though you are a US citizen or a green card holder( a US resident) are not still liable for the gift tax (UNLESS you made a gift exceeding $1.13,000 million to your son)due to the unified wealth transfer tax credit.
“그리고 세제를 조금이라도 감면할수 있는 방법이 있는지 전문가님들의 답변부탁드립니다.”--->As described above, you are NOT subject to US gift tax on the gift given to your son in US.